Repeating noise suppression for array print check inspection

A non-transitory computer-readable medium, storing program instructions executed on a computer system for performing a computer-implemented method for detecting defects on a reticle, wherein the computer-implemented method comprises:

• acquiring images of patterned features formed in an array region on a wafer generated by an inspection subsystem, wherein a reticle is used to print the patterned features on the wafer in a lithography process;
• when a pitch of the patterned features in an instance of a care area in the images is not an integer of pixels in a detector of the inspection subsystem, interpolating a portion of the images in the instance of the care area to generate an interpolated care area image having a modified pitch of the patterned features in the interpolated care area image that is an integer of the pixels;
• generating difference images for multiple instances of the care area in the images, wherein generating at least one of the difference images comprises subtracting the interpolated care area image from an additional portion of the images in at least one of the multiple instances of the care area;
• stacking the difference images to generate a stacked difference image;
• detecting defect candidates in the care area by applying a defect detection method to the stacked difference image;
• and
• identifying defects on the reticle based on the detected defect candidates, wherein said acquiring, interpolating, generating, stacking, detecting, and identifying are performed by the computer system coupled to the inspection subsystem.

A computer-implemented method for detecting defects on a reticle, comprising:

• acquiring images of patterned features formed in an array region on a wafer generated by an inspection subsystem, wherein a reticle is used to print the patterned features on the wafer in a lithography process;
• when a pitch of the patterned features in an instance of a care area in the images is not an integer of pixels in a detector of the inspection subsystem, interpolating a portion of the images in the instance of the care area to generate an interpolated care area image having a modified pitch of the patterned features in the interpolated care area image that is an integer of the pixels;
• generating difference images for multiple instances of the care area in the images, wherein generating at least one of the difference images comprises subtracting the interpolated care area image from an additional portion of the images in at least one of the multiple instances of the care area;
• stacking the difference images to generate a stacked difference image;
• detecting defect candidates in the care area by applying a defect detection method to the stacked difference image;
• and
• identifying defects on the reticle based on the detected defect candidates, wherein said acquiring, interpolating, generating, stacking, detecting, and identifying are performed by a computer system coupled to the inspection subsystem.